<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div>
  <input type="text" v-model="n1">
  <input type="text" v-model="n2">
  <input type="button" value="加" @click="f(1)">
  <input type="button" value="减" @click="f(2)">
  <input type="button" value="乘" @click="f(3)">
  <input type="button" value="除" @click="f(4)">
  <div>结果:{{result}}</div>
</div>
<script src="js/vue.min.js"></script>
<script>
    let v = new Vue({
      el:"body>div",
      data:{
        n1:"",n2:"",result:""
      },
      methods:{
        f(x){
            if (isNaN(v.n1)||isNaN(v.n2)){
              v.result = "输入错误!";
              return;
            }
            switch (x) {
              case 1:
                v.result = v.n1*1+v.n2*1;
                break;
              case 2:
                v.result = v.n1-v.n2;
                break;
              case 3:
                v.result = v.n1*v.n2;
                break;
              case 4:
                v.result = v.n1/v.n2;
                break;
            }
        }
      }
    })
</script>
</body>
</html>